U.S. patent number 6,921,567 [Application Number 10/166,746] was granted by the patent office on 2005-07-26 for disk recording medium.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Yasushi Endo, Shinichi Kato, Kengo Oishi.
United States Patent |
6,921,567 |
Oishi , et al. |
July 26, 2005 |
Disk recording medium
Abstract
A disk recording medium of the present invention comprises an
antimicrobial agent and an antifungal agent.
Inventors: |
Oishi; Kengo (Kanagawa,
JP), Kato; Shinichi (Kanagawa, JP), Endo;
Yasushi (Kanagawa, JP) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JP)
|
Family
ID: |
27346924 |
Appl.
No.: |
10/166,746 |
Filed: |
June 12, 2002 |
Foreign Application Priority Data
|
|
|
|
|
Jun 13, 2001 [JP] |
|
|
P.2001-178727 |
Jul 6, 2001 [JP] |
|
|
P.2001-206762 |
Jul 30, 2001 [JP] |
|
|
P.2001-229765 |
|
Current U.S.
Class: |
428/64.1;
428/64.4; 430/270.11; G9B/7.159; G9B/7.171 |
Current CPC
Class: |
G11B
7/24097 (20130101); G11B 7/252 (20130101); G11B
7/256 (20130101); G11B 7/2585 (20130101); Y10T
428/21 (20150115) |
Current International
Class: |
G11B
7/24 (20060101); G11B 7/257 (20060101); B32B
003/02 () |
Field of
Search: |
;428/64.1,64.4,913
;430/270.11,495.1,945 ;369/283,275.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Database WPI, Section Ch, Week 198813, Derwent Publications Ltd.,
London, GB; Class A89, AN 1988-088051, XP-0022255876 and JP 63
039159 A..
|
Primary Examiner: Mulvaney; Elizabeth
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A disk recording medium comprising a printing layer provided on
one side thereof, wherein the printing layer contains at least one
of an antimicrobial agent and an antifungal agent, the printing
layer is formed by a printing ink, and the printing layer contains
an ultraviolet-curing resin.
2. The disk recording medium according to claim 1, which comprises:
the printing layer provided on one side thereof; and a layer
containing at least one of the antimicrobial agent and the
antifungal agent, in which the layer is provided on the printing
layer.
3. The disk recording medium according to claim 1, wherein the
printing ink is subject to an ultraviolet-curing treatment after
coating.
4. The disk recording medium according to any one of claims 1, and
2, wherein the layer containing at least one of the antimicrobial
agent and the antifungal agent is provided on at least one of an
outer periphery and inner periphery of the disk recording medium.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk recording medium such as
optical disk and photomagnetic disk.
2. Description of the Related Art
As a disk recording medium which is used left unreceived in a
cartridge, i.e., in a so-called single form there is known one
comprising a printing surface provided on one side thereof and a
recording surface provided on the other. A printing layer is formed
by a printing ink on the printing surface. The printing surface
displays the contents of data recorded in the disk recording
medium. As such a disk recording medium there is known an optical
disk such as musical CD and CD-R.
Such a disk recording medium is often received and stored in a
plastic case when not in use. The plastic case also receives an
index card (title card) indicating the contents of data recorded in
the disk recording medium.
For example, when a disk recording medium is stored in a plastic
case at a proper temperature and humidity for a long period of
time, fungi can grow on the index card or disk recording medium
(particularly on the printing surface) because the paper fiber
constituting the index card or the printing layer in the disk
recording medium contains nutrient. Further, when the user handles
the index card, the disk recording medium and the plastic case,
they are stained with dirt or oil of the user's hand that causes
the proliferation of fungi.
In particular, since the paper fiber constituting the index card
exerts a great moisture-retaining effect, fungi which has grown on
the index card can easily move to the surroundings. When fungi
which has grown on the index card moves to the plastic case or disk
recording medium, fungi can acceleratedly grow on the plastic case
or the printing surface of the disk recording medium.
The printing surface of the disk recording medium stained with
fungi apparently has an outstanding dirt that lowers the credit
thereof with the user and hence the commercial value. Further, when
the recording surface of the disk recording medium is stained with
fungi which has moved from the printing surface or the like, normal
reading and writing of recorded data cannot be performed.
The recent high capacity optical disk (e.g., DVD) is required to
use a recording light beam having a very small spot diameter in
order to accomplish high density recording. To this end, a laser
source having a short wavelength is used. Alternatively, the
aperture of lens is raised. Such an optical disk tends to have a
very small distance between the recording surface and the
condenser. When the recording surface of the optical disk has
fungi, the fungi can move to laser pick up lens or the interior of
drive, making it unlikely that normal reading and writing of
recorded data can he performed.
SUMMARY OF THE INVENTION
The invention has been worked out under these circumstances. An
object of the invention is to provide a disk recording medium which
can be remarkably prevented from proliferation or attachment of
fungi.
The object of the invention is accomplished with a disk recording
medium as mentioned below. (1) A disk recording medium comprising
at least one of an antimicrobial agent and an antifungal agent. (2)
The disk recording medium according to the item (1), which
comprises on the recording surface thereof a layer containing at
least one of the antimicrobial agent and the antifungal agent. (3)
The disk recording medium according to the items (1) or (2), which
comprises a printing layer provided on one side thereof, wherein
the printing layer contains at least one of the antimicrobial agent
and the antifungal agent. (4) The disk recording medium according
to any one of the items (1) to (3), which comprises:
a printing layer provided on one side thereof; and
a layer containing at least one of the antimicrobial agent and the
antifungal agent, in which the layer is provided on the printing
layer. (5) The disk recording medium according to the item (3),
wherein the printing layer is formed by a printing ink containing
at least one of the antimicrobial agent and the antifungal agent.
(6) The disk recording medium according to the item (5), wherein
the printing ink contains an ultraviolet-curing resin. (7) The disk
recording medium according to the item (6), wherein the printing
ink is subject to an ultraviolet-curing treatment after coating.
(8) The disk recording medium according to any one of the items (2)
to (4), wherein the layer containing at least one of the
antimicrobial agent and the antifungal agent is provided on at
least one of an outer periphery and inner periphery of the disk
recording medium.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a conceptional perspective view illustrating a first
embodiment of implementation of the invention;
FIG. 2 is a conceptional perspective view illustrating a second
embodiment of implementation of the invention;
FIG. 3 is a conceptional sectional view illustrating a second
embodiment of implementation of the invention;
FIG. 4 is a conceptional sectional view illustrating a third
embodiment of implementation of the invention;
FIG. 5 in a conceptional sectional view illustrating a fourth
embodiment of implementation of the invention;
FIG. 6 is a conceptional sectional view illustrating a fifth
embodiment of implementation of the invention.
FIG. 7 is a conceptional perspective view illustrating a sixth
embodiment of implementation of the invention;
FIG. 8 is a longitudinal sectional view of FIG. 7;
FIG. 9 is a diagram illustrating the process for the production of
the sixth embodiment of the invention.
FIG. 10 is a conceptional perspective view illustrating a seventh
embodiment of implementation of the invention;
FIG. 11 is a sectional view illustrating the layer structure of the
disk recording medium of FIG. 10; and
FIG. 12 is a sectional view illustrating an eighth embodiment of
implementation of the invention.
DESCRIPTION OF THE REFERENCE NUMERALS AND SIGNS 10, 20, 30, 40, 50,
100, 110 Disk recording medium 11, 21, 31, 41, 51 Substrate 12, 42,
52 Antimicrobial/antifungal layer 22a, 32a Antimicrobial/antifungal
layer on the outer periphery 22b, 32b Antimicrobial/antifungal
layer on the inner periphery 18, 48 Printing layer 38 Dummy
Substrate
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the layer containing at least one of the
antimicrobial agent and the antifungal agent (including the
printing layer containing at least one of the antimicrobial agent
and the antifungal agent) also is referred to as an
antimicrobial/antifungal layer.
The aforementioned printing ink preferably comprises an
ultraviolet-curing resin (UV-curing resin) incorporated
therein.
Further, the aforementioned printing layer preferably is formed by
applying the desired composition to the disk recording medium by a
known printing method such as pad printing, and then subjecting the
coat layer to ultraviolet curing.
Moreover, the aforementioned antimicrobial/antifungal layer
preferably is provided at least on the outer periphery of the disk
recording medium. More preferably, the aforementioned
antimicrobial/antifungal layer is provided also in the inner
periphery of the disk recording medium.
As the antifungal agent there may be used any of various known
antifungal agents. Examples of these antifungal agents include
volatile antifungal agent such as bromocinnamaldehyde and
2-isopropyl-5-methylphenol, and nonvolatile antifungal agent such
as 2-(4-thiazolyl)-benzimidazole, benzyl bromoacetate and
N-dimethyl-N'-phenol-N'-(fluorodichloromethylthio)sulfamide.
The content of the antifungal agent is preferably, e.g., from 1% to
10% by weight, based on the total weight of the
antimicrobial/antifungal layer.
Examples of the antimicrobial agent include silicate-based
antimicrobial agent such as zeolite (crystalline aminosilicate),
clay mineral and silica gel, phosphate-based antimicrobial agent
such as zirconium phosphate and calcium phosphate, and so-called
inorganic antimicrobial agent comprising silver adsorbed to and
supported on an inorganic particulate carrier such as particulate
soluble glass, activated charcoal, metal, alloy, organic metal and
titanium oxide. An organic antimicrobial agent may be used.
The content of the antimicrobial agent varies with the kind of the
antimicrobial agent used but is preferably from 0.1% to 10% by
weight, more preferably from 0.5% to 8% by weight based on the
total weight of the antimicrobial/antifungal layer, if the
antimicrobial agent is a silver-substituted zeolite.
In accordance with the aforementioned arrangement of disk recording
medium, the antifungal agent or antimicrobial agent contained in
the printing layer can remarkably prevent the proliferation of
fungi on the disk recording medium. The use of this disk recording
medium makes the proliferation of fungi difficult also on index
card and plastic case.
When the printing ink comprises an ultraviolet-curing resin
incorporated therein, the printing ink can be irradiated with
ultraviolet rays to undergo rapid curing, making it possible to
enhance the productivity. Further, irradiation with ultraviolet
rays can be expected to exert sterilizing effect. In other words,
irradiation with ultraviolet rays can annihilate various bacteria
on the surface of the disk (once in the production process), making
it possible to remarkably prevent the proliferation of fungi.
The results of observation show that fungi can easily grow at the
edge (periphery) of the disk recording medium. For example, the
periphery of the disk recording medium is often brought into
contact with the hand of the user or index card. This probably
causes the proliferation of fungi. Thus, by providing a printing
layer containing a antifungal agent or antimicrobial agent on the
periphery of or in the interior of the disk by pad printing or the
like, the proliferation of fungi on the disk recording medium can
be remarkably prevented.
The term "recording surface" as used herein is meant to indicate
the surface to be irradiated with recording light beam or
reproducing light beam. The recording surface may be one surface or
the other surface of the disk recording medium.
An antimicrobial/antifungal layer may be provided on the disk
recording medium all over the entire surface thereof. However, an
annular antimicrobial/antifungal layer is preferably provided on at
least one of the outer periphery and the inner periphery of the
disk recording medium.
In general, the user often touches at least one of the periphery
and the inner side of the disk recording medium when mounting the
disk recording medium on the drive device or taking it out of the
drive device. Therefore, nutrients (dirt and oil such as
fingerprint) necessary for the growth of fungi are moved from the
user's hand to the periphery or inner side of the disk recording
medium. Mildew can grow there. Further, fungi can move to the
recording surface or printing surface of the disk recording
medium.
The aforementioned arrangement of the disk recording medium can
exert an enhanced antimicrobial and sterilizing effect on the
periphery or inner side of the disk recording medium, making it
possible to effectively prevent the proliferation of fungi.
The antimicrobial/antifungal layer is preferably provided on the
non-recording area such as outer periphery and inner periphery of
the disk recording medium. The antimicrobial/antifungal layer may
be provided also on the periphery or inner side of the disk
recording medium perpendicular to the recording surface
thereof.
When the antimicrobial/antifungal layer is provided on the
non-recording area such as outer periphery and inner periphery of
the disk recording medium, there are no effects of the
antimicrobial/antifungal layer on the optical properties of the
disk recording medium, making it possible to perform smoother
recording/reproduction.
The antimicrobial agent and antifungal agent may be used in the
form of solution in water or other solvents. Further, the
antimicrobial/antifungal layer may be formed by applying a mixture
of the antimicrobial agent with a resin or a solution of the
antimicrobial agent in the resin.
As the method for applying the antimicrobial agent or the
antifungal agent, there may be used any of various methods such as
coating with roller or brush, dip coating, spin coating and padding
(pad printing).
In accordance with the disk recording medium of the invention,
antimicrobial/antifungal layer is provided on the printing layer of
the disk recording medium, making it possible to prevent the
proliferation of fungi on the surface of the disk over an extended
period of time. This makes it possible to perform
recording/reproduction in a stable manner without impairing the
reliability of the disk recording medium. This also makes it
possible to exert an effect of protecting the printing layer.
The aforementioned antimicrobial/antifungal layer may be an
overcoat layer of an antimicrobial agent or an antifungal agent
provided on the printing layer of the disk recording medium or may
be a protective layer made of an acrylic resin. This
antimicrobial/antifungal layer can be formed by a simple working
process without complicating the process for the production of the
disk recording medium, making it possible to produce a high
performance disk recording medium at a reduced cost.
Embodiments of implementation of the invention will be described in
detail in connection with the attached drawings. A disk recording
medium 10 according to the first embodiment shown in FIG. 1
comprises a recording surface provided on one side thereof (upper
side in the drawing) and a printing surface provided on the other
(lower side in the drawing). The disk recording medium 10 comprises
a disk-shaped resin substrate 11 having a central hole 11a and an
antimicrobial/antifungal layer 12 containing an antimicrobial agent
provided on one surface of the substrate 11. Though not shown, a
recording layer, a reflective layer and other layers may be
provided on the substrate 11.
In the present embodiment, the antimicrobial/antifungal layer 12 is
provided all over the entire surface thereof.
In accordance with the aforementioned arrangement of the disk
recording medium 10, there is provided the antimicrobial/antifungal
layer 12 containing an antimicrobial agent that exerts an enhanced
antimicrobial and sterilizing effect on the recording layer. In
this arrangement, the proliferation of fungi can be remarkably
prevented. The sterilizing effect of the antimicrobial/antifungal
layer 12 on the recording surface makes it possible to prevent the
proliferation of fungi also on the printing surface of the disk
recording medium 10. Further, the use of this disk recording medium
10 makes it difficult for fungi to grow also on the index card or
plastic case.
FIG. 2 illustrates a second embodiments of implementation of the
invention. A disk recording medium 20 comprises a recording surface
provided on one side (upper side in the drawing) and a printing
surface provided on the other (lower side in the drawing). The
outer periphery and inner periphery of the disk recording medium 20
form non-recording areas 23a and 23b, respectively, which are not
irradiated with recording light beam or reproducing light beam. The
annular region provided between the non-recording area 23a on the
periphery and the non-recording area 23b on the inner side acts as
a recording area 23 which is irradiated with a recording light beam
or reproducing light beam.
A conceptional longitudinal sectional view of the disk recording
medium 20 is shown in FIG. 3.
In the present embodiments of implementation of the invention,
annular antimicrobial/antifungal layer 22a and 22b containing an
antimicrobial agent are provided on the non-recording area on the
recording surface. In some detail, the antimicrobial layer 22a is
provided on the periphery of the substrate 21 and the
antimicrobial/antifungal layer 22b is provided on the inner side of
the substrate 21.
When carrying the disk recording medium 20, the user often grips
the periphery and the inner side of the disk recording medium 20,
causing these areas to be stained with dirt and oil of the hand.
However, since the outer periphery and inner periphery of the disk
recording medium 20 allow the antimicrobial/antifungal layers 22a
and 22b, respectively, to exert an enhanced antimicrobial and
sterilizing effect, the proliferation of fungi on the outer
periphery and inner periphery of the disk recording medium 20 can
be remarkably prevented.
FIG. 4 illustrates a third embodiments of implementation of the
invention. A disk recording medium 30 comprises a recording surface
provided on both sides thereof (one side shown as an upper side and
the other shown as a lower side).
Antimicrobial/antifungal layers 32a and 32b are provided on the
non-recording area (outer periphery and inner periphery) of both
the recording areas.
In accordance with the aforementioned arrangement of the disk
recording medium 30, the proliferation of fungi on the outer
periphery and inner periphery thereof can be remarkably
prevented.
FIG. 5 illustrates a fourth embodiments of implementation of the
invention. The present embodiment comprises a recording surface
provided on one side thereof (upper side in the drawing) and a
printing surface (lower side in the drawing).
The disk recording medium 40 comprises an antimicrobial/antifungal
layer containing an antimicrobial agent provided on the edge of the
periphery of the disk recording medium 40. In some detail, an
antimicrobial/antifungal layer 42 containing an antimicrobial agent
is provided extending over the periphery of the recording surface,
the periphery of the printing surface and the periphery of the
substrate 41.
When carrying the disk recording medium 40, the user often grips
the periphery of the disk recording medium 40, causing this area to
be stained with dirt and oil of the hand. However, the disk
recording medium 40 allows the antimicrobial/antifungal layer 42
provided extending over the periphery of the recording surface, the
periphery of the printing surface and the periphery of the
substrate 41 to remarkably prevent the proliferation of fungi on
the periphery of the disk recording medium 40.
FIG. 6 is a fifth embodiments of implementation of the invention.
The present embodiment comprises a recording surface provided on
one side thereof (upper side in the drawing) and a printing surface
provided on the other (lower side in the drawing).
The disk recording medium 50 comprises an antimicrobial/antifungal
layer containing an antimicrobial agent provided on the edge of the
inner side thereof. In some detail, an antimicrobial/antifungal
layer 52 containing an antimicrobial agent is provided extending
over the inner side of the recording surface, the inner side of the
printing surface and the inner side of the substrate 51. In other
words, the antimicrobial/antifungal layer 52 is provided also on
the cylindrical surface defining a central hole 51a.
In the central hole 51a is fitted a retaining member provided on a
plastic case which is not shown. Mildew which has grown on the
plastic case or which has moved from the index card to the plastic
case tries to move to the inner side of the disk recording medium
50 via the retaining member. However, the inner side of the disk
recording medium 50 allows the antimicrobial/antifungal layer 52 to
exert an enhanced antimicrobial and sterilizing effect, fungi
cannot move to the disk recording medium 50.
The invention is not limited to the aforementioned embodiment, but
proper modifications and changes can be made therein.
The aforementioned embodiments may be combined. For example, both
an antimicrobial/antifungal layer extending over the periphery of
the recording surface, the periphery of the printing surface and
the periphery of the substrate and an antimicrobial/antifungal
layer extending over the inner side of the recording surface, the
inner side of the printing surface and the inner side of the
substrate may be provided.
An antimicrobial/antifungal layer layer according to the
aforementioned the second embodiment may be provided also on the
disk recording medium comprising a recording surface provided on
both sides thereof.
FIG. 7 illustrates a sixth embodiment of implementation of the
invention.
A disk recording medium (optical disk) 60 shown in FIG. 7 comprises
a printing surface provided on one side (upper side in the drawing)
and a recording surface provided on the other. The optical disk 60
comprises a disk-shaped resin substrate 11 having a central hole
11a and a printing layer 18 provided on one side thereof. A
recording layer, a reflective layer and other layers are provided
interposed between the substrate 11 and the printing layer 18 but
are not shown.
In the present embodiment, the printing layer 18 consists of three
regions. A first region 18a is provided along the periphery of the
substrate 11. A second region 18b is provided along the inner side
of the substrate 11. A third region 18c is provided interposed
between the first region 18a and the second region 18b. The fist,
second and third regions 18a, 18b and 18c are annular and almost
concentric as viewed from above. Almost all the region between the
first region 18a and the second region 18b forms the third region
18c.
A conceptional longitudinal sectional view of the optical disk 60
is shown in FIG. 8. The printing ink forming the first region 18a
and the printing ink forming the second region 18b each comprise at
least one of a antifungal agent and an antimicrobial agent and an
ultraviolet-curing resin incorporated therein besides the pigment.
The printing ink forming the third region 18c comprises an
ultraviolet-curing resin incorporated therein besides the
pigment.
The third region 18c displays the contents of data recorded in the
optical disk, design pattern, kind of disk, etc.
As an example of the process for the production of the optical disk
60, a process by pad printing will be described below. Firstly, as
shown in FIG. 9A, a first region 18a of printing layer is provided
on the periphery of the substrate 11 using a pad 200. After the
drying of the first region 18a at an ultraviolet irradiation step
(not shown), a second region 18b of printing layer is then provided
on the inner side of the substrate 11 as shown in FIG. 9B. After
the drying of the second region 18b at the ultraviolet irradiation
step, a third region 18c is then provided between the first region
18a and the second region 18b as shown in FIG. 9C. Thereafter, the
third region 18c is similarly dried at the ultraviolet irradiation
step.
The ultraviolet curing treatment may be accomplished also by
providing the printing layers 18a, 18b and 18c on the substrate,
and then subjecting the coated substrate to irradiation with UV
altogether.
In accordance with the aforementioned arrangement of the optical
disk 60, the antifungal agent or antimicrobial agent contained in
the first region 18a and the second region 18b of the printing
layer 18 makes it possible to remarkably prevent the proliferation
of fungi on the printing surface of the optical disk 60. The
printing surface of the optical disk 60 is opposed to the index
card (not shown) when received in a plastic case which is not
shown. Under these conditions, the index card can be brought into
contact with the periphery of the optical disk 60. However, since
the first region 18a of the printing layer comprises a antifungal
agent or antimicrobial agent incorporated therein, fungi which has
possibly grown on the index card cannot move to the periphery of
the optical disk 60. Further, when the user takes the optical disk
60 out of the plastic case or carries the optical disk 60, the user
often grips the periphery and the inner side of the optical disk
60, causing these areas to be stained with dirt and oil of the
user's hand. However, the antifungal agent or antimicrobial agent
contained in the first region 18a and the second region 18b of the
printing layer can remarkably prevent the proliferation of fungi on
the outer periphery and inner periphery of the optical disk 60.
The optical disk 60 not only is insusceptible to proliferation of
fungi on the printing surface thereof but also prevents fungi which
has grown on the index card from moving to the printing surface
opposed to the index card. Accordingly, the optical disk 60 is
subject to neither proliferation nor reception of fungi on the
recording surface thereof, which is provided opposite the printing
surface.
The use of the optical disk 60 also allows the antifungal agent or
antimicrobial agent contained in the first region 18a and the
second region 18b of the printing layer to exert its effects,
making it difficult for fungi to grow also on the index card and
plastic case.
The optical disk 60 can be irradiated with ultraviolet rays on the
printing ink containing an ultraviolet-curing resin so that the
printing ink can be rapidly cured, making it possible to enhance
the productivity thereof. Further, various bacteria on the surface
of the optical disk 60 can be once annihilated by ultraviolet rays
at the production step, making it possible to remarkably prevent
the proliferation of fungi.
The invention is not limited to the aforementioned embodiment, but
proper modifications and changes can be made therein.
For example, the third region of the printing layer may comprise a
antifungal agent or antimicrobial agent incorporated therein. The
printing layer may comprise a antifungal agent or antimicrobial
agent incorporated therein all over the area thereof.
For example, the printing layer comprising a antifungal agent or
antimicrobial agent incorporated therein on the first region,
second region or the like may be free of pigment to form a
transparent or semi-transparent layer.
FIG. 10 is a general perspective view of a disk recording medium
(compact disk CD) 100 according to a seventh embodiment of
implementation of the invention. FIG. 11 is a sectional view
illustrating the layer structure of the disk recording medium of
FIG. 10.
As shown in FIG. 7, the disk recording medium 100 according to the
present embodiment comprises a recording layer 15 formed on one
side of a substrate 11 made of a transparent resin, a reflective
layer 14 such as vacuum deposit of aluminum, a protective layer 16,
a printing layer 18, and a antimicrobial/antifungal layer 12
laminated in this order.
Referring to the method for preparing the disk recording medium 100
according to the present embodiment, a photosensitive agent
(resist) is applied to a polished glass disk. The coated material
is irradiated with laser beam to perform recording of signal
thereon, and then subjected to development to form pits
corresponding to the signal. Nickel is then deposited on the glass
disk to a great thickness to obtain a master. The master is then
reproduced to prepare a stamper. With this stamper put in a mold,
injection molding is then effected with a transparent resin. In
this manner, a molded product having a recording layer 15
transferred to one side thereof is obtained. A reflective layer 14
made of aluminum or the like is then formed by sputtering or the
like. A protective material is then applied to the reflective layer
14 to form a protective layer 16 thereon. Thereafter, a label is
printed on the protective layer 16 by padding, screen printing or
the like to form a printing layer 18. Thus, a completed product is
obtained.
The disk recording medium 100 of the present embodiment is obtained
by applying a antifungal agent to the printing layer 18 of the
completed product thus obtained to form a antimicrobial/antifungal
layer 12. As the coating method there may be used, e.g., spin
coating method.
As the antifungal agent there may be used any of various types of
antifungal agents. In particular, a volatile antifungal agent such
as bromocinnamaldehyde and 2-isopropyl-5-methylphenol or a
nonvolatile antifungal agent such as 2-(4-thiazolyl)-benzimidazole,
benzyl bromoacetate and
N-dimethyl-N'-phenol-N'-(fluorodichloromethylthio) sulfamide is
preferably used. Besides these antifungal agents, various
antifungal agents for plastic may be used.
Due to the antifungal effect of the antimicrobial/antifungal layer
12, the disk recording medium 100 according to the present
embodiment is little likely to have fungi grown thereon even when
stored in a case or the like for a long period of time and thus can
perform fair recording/reproduction of data over an extended period
of time. The same effect can be obtained with various CD's (e.g.,
CD-ROM, CD-R (recordable), CD-RW (rewritable)).
A modification of the disk recording medium according to the
present embodiment will be described hereinafter.
Though not shown, the modification of the disk recording medium has
the same antimicrobial/antifungal layer 12 as in the disk recording
medium 100 according to the aforementioned embodiment except that
it is formed by an acrylic resin. This modification of disk
recording medium is prepared by the same method as for the
aforementioned embodiment except for the uppermost acrylic resin
layer. In some detail, an acrylic resin layer having a antifungal
effect is formed on the printing layer 18 having data or the like
printed thereon by a method which comprises sticking an acrylic
resin sheet, a method which comprises applying a liquid acrylic
resin or the like.
This acrylic resin has an effect of making the proliferation of
fungi difficult even at a high temperature and humidity. The reason
for this effect is unknown. However, this is presumably because
residual acrylic acid monomer contained in the acrylic fiber
contributes to the antifungal effect.
Accordingly, due to the antifungal effect of the acrylic resin
itself, this modification of the disk recording medium is little
likely to have fungi grown thereon even when stored for a long
period of time and thus can perform fair recording/reproduction of
data over an extended period of time.
An eighth embodiment of the disk recording medium according to the
invention will be described hereinafter.
FIG. 12 is a sectional view illustrating the layer structure of a
disk recording medium (digital video disk DVD) 110 according to the
present eighth embodiment. The disk recording medium 110 comprises
a recording layer 35 formed on one side of a substrate 21 made of a
transparent resin, a reflective layer 34 such as vacuum deposit of
aluminum, and a protective layer (adhesive layer) 36 laminated in
this order. A dummy substrate 38 is connected to the upper surface
of the laminate with the protective layer 30 as an adhesive layer.
A protective layer 40, a printing layer 48 and an
antimicrobial/antifungal layer 42 are formed on the dummy substrate
38 on the side thereof opposite the adhesive layer 36. Thus, the
disk recording medium of the present embodiment has the same
structure as ordinary single-layer DVD except the uppermost
antimicrobial/antifungal layer 42 of the disk recording medium
110.
In some detail, the disk recording medium 110 of the present
embodiment is prepared by applying the aforementioned antifungal
agent to the upper surface of the printing layer 48 having various
data or the like printed thereon by spin coating method or the like
to form a antimicrobial/antifungal layer 42 thereon.
This disk recording medium 110 is little likely to have fungi grow
thereon even when stored at a high temperature and humidity for a
long period of time and thus can perform fair
recording/reproduction over an extended period of time.
As well known, while CD has a storage capacity of 650 MB, DVD,
though in various forms, has a storage capacity of 4.7 GB on one
side thereof or 8.5 GB in the case of two-layer structure.
Accordingly, CD has a track pitch of 1.33 .mu.m and DVD has a
standard track pitch of 0.74 .mu.m and thus has a high density
recording structure having data recording pits disposed also in the
direction of track. In addition, the recent trend is for more light
pickup devices for DVD to have a narrow distance between the disk
recording medium and the light pickup during
recording/reproduction.
Therefore, DVD can undergo troubles in data recording/reproduction
due to fungi on the surface of the disk and foreign matters
attached thereto which don't affect CD. While CD is prepared by
laminating on a substrate having a thickness of 1.2 mm, DVD is
prepared by laminating on a substrate having a thickness as small
as 0.6 mm. Accordingly, the ratio of size of fungi and foreign
matters to the size of beam spot is much higher on DVD than on CD.
Combined with the aforementioned rise of recording density, fungi
and foreign matters can easily cause errors on DVD.
A modification of the present embodiment will be described
hereinafter.
Though not shown, this modification of disk recording medium
comprises the same antimicrobial/antifungal layer 42 as in the disk
recording medium of the aforementioned embodiment except that it is
formed by an acrylic resin. The acrylic resin layer may be formed
by a method which comprises sticking an acrylic resin sheet or a
method which comprises applying a liquid acrylic resin.
In the aforementioned arrangement, the uppermost acrylic resin
layer has a antifungal layer as in the previous modification.
Accordingly, the disk recording medium 110 is little likely to have
fungi grown thereon even at a high temperature and humidity for a
long period of time and thus can perform fair
recording/reproduction over an extended period of time.
The aforementioned embodiments each represent an example of the
invention and the invention is not limited thereto. Proper
modifications and improvements may be made in the invention so far
as the essence of the invention is not changed.
In accordance with the disk recording medium of the invention, the
proliferation of fungi on the disk recording medium can be
strikingly prevented for a long period of time, and the movement of
fungi to other sites such as case in which it is received can be
prevented, making it possible to enhance the reliability of the
disk recording medium.
The entire disclosure of each and every foreign patent application
from which the benefit of foreign priority has been claimed in the
present application is incorporated herein by reference, as if
fully set forth.
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